Device for characterizing an interface of a structure and corresponding device

Abstract

The present invention relates to a device ( 1 ) for characterizing an interface of a structure ( 6 ), said structure ( 6 ) comprising a solid first material and a second material, the materials being separated by said interface. The device ( 1 ) comprises: means ( 2 ) for generating a first mechanical wave; means ( 2 ) for forming Brillouin oscillations; means ( 10 ) for detecting time variation of the Brillouin oscillations; means ( 12 ) for responding to the time variation of the Brillouin oscillations to identify reflection of said first mechanical wave by said interface or transmission through said interface of a second mechanical wave interfering with the first mechanical wave; and means ( 13 ) for determining the variation in amplitude of the Brillouin oscillations before and after reflection or transmission by said interface. The invention also relates to a corresponding method of characterization.

The invention claimed is: 
     
       1. A device configured to characterize an interface of a structure, said structure comprising a solid first material and a second material, which materials are separated by said interface, the device comprising:
 a generator configured to generate a first mechanical wave in the solid first material; 
 a generator configured to generate probe radiation configured to propagate at least in part in the solid first material so as to form Brillouin oscillations; and 
 a detector configured to detect the variation in time of the Brillouin oscillations in the solid first material; 
 wherein the device further comprises: 
 an identification device configured to use the time variation of the Brillouin oscillations in the solid first material to identify reflection of said first mechanical wave by said interface or transmission through said interface of a second mechanical wave interfering with the first mechanical wave; and 
 a determination device configured to determine the variation in amplitude of the Brillouin oscillations in the solid first material before and after reflection or transmission by said interface. 
 
     
     
       2. The device according to  claim 1 , wherein the determination device is configured to determine the variation in amplitude of the Brillouin oscillations as a function of the wavelength of the probe radiation. 
     
     
       3. The device according to  claim 1 , wherein the second material is a gas, and wherein:
 the identification device is configured to identify a reflection of said first mechanical wave by said interface; and 
 the determination device is configured to determine the variation in amplitude of the Brillouin oscillations before and after reflection by said interface, in order to characterize the roughness of said interface. 
 
     
     
       4. The device according to  claim 3 , wherein the generator configured to generate probe radiation is configured to change the wavelength of the probe radiation as a function of the size of the roughness to be measured. 
     
     
       5. The device according to  claim 1 , wherein the second material is a solid thin layer, and wherein:
 the identification device is configured to identify transmission by said interface of a second mechanical wave interfering with the first mechanical wave; and 
 the determination device is configured to determine the variation in amplitude of the Brillouin oscillations before and after transmission by said interface of the second mechanical wave, in order to characterize the acoustic transmission coefficient of said interface. 
 
     
     
       6. The device according to  claim 5 , wherein the generator configured to generate a first mechanical wave in the solid first material is configured to form the first and second mechanical waves simultaneously respectively in the solid first material and in the second material. 
     
     
       7. The device according to  claim 5 , further comprising an adjustment device configured to adjust parameters of a theoretical model giving the values for variation in amplitude of the Brillouin oscillations for different probe radiation wavelengths, in order to obtain the amplitude variation of the Brillouin oscillations as determined by the determination device, with the parameters as adjusted in this way serving to characterize the interface. 
     
     
       8. A method of characterizing an interface of a structure, said structure comprising a solid first material and a second material, which materials are separated by said interface, the method comprising the following steps:
 forming a first mechanical wave in the solid first material; 
 generating a probe radiation; 
 forming Brillouin oscillations with probe radiation propagating at least in part in the solid first material; and 
 detecting the time variation of the Brillouin oscillations in the solid first material; 
 wherein the method further comprises the following steps: 
 identifying reflection of said first mechanical wave by said interface or transmission through said interface of a second mechanical wave interfering with the first mechanical wave on the basis of the time variation of the Brillouin oscillations in the solid first material; and 
 determining the variation in amplitude of the Brillouin oscillations in the solid first material before and after reflection or transmission by said interface. 
 
     
     
       9. The method according to  claim 8 , wherein the variation in amplitude of the Brillouin oscillations as a function of the wavelength of the probe radiation is determined. 
     
     
       10. The method according to  claim 8 , wherein the second material is a gas, and wherein a reflection of said first mechanical wave by said interface is identified, and the variation in amplitude of the Brillouin oscillations before and after reflection by said interface is determined in order to characterize the roughness of said interface. 
     
     
       11. The method according to  claim 10 , wherein the wavelength of the probe radiation is selected as a function of the size of the roughness to be measured. 
     
     
       12. The method according to  claim 8 , wherein the second material is a solid thin layer, and wherein transmission through said interface of a second mechanical wave interfering with the first mechanical wave is identified, and the variation in amplitude of the Brillouin oscillations before and after transmission by said interface of the second mechanical wave is determined in order to characterize the acoustic transmission coefficient of said interface. 
     
     
       13. The method according to  claim 12 , wherein the first and second mechanical waves are formed simultaneously respectively in the solid first material and in the second material. 
     
     
       14. The method according to  claim 9 , wherein the parameters of a theoretical model giving the values for variation in amplitude of the Brillouin oscillations for different wavelengths of the probe radiation are adjusted in order to obtain the variations in amplitude of the Brillouin oscillations as determined, with the parameters as adjusted in this way serving to characterize the interface.